Long-Term Mechanical Behavior of Fiber Reinforced Plastics

1 Long-Term Mechanical Behavior of Fiber Reinforced Plastics 

Long-term tests under static load are performed under a variety of conditions e.g., under tensile, compressive, bending and flexural loads, under uni- or multi-axial load, under combined load, and as a function of temperature, processing influences, environmental conditions and depending on design features (notch factor). In practice, creep tests are typically performed under tensile load. 

The tendency to creep is lower in reinforced plastics than unreinforced plastics. The most important test methods are the creep-rupture (o = const.) and relaxation tests (e = const.). 

Creep tendency in glass and carbon fibers is very low, in aramid fibers it is higher. In combination with organic matrices or adhesives, their viscoelastic behavior determines creep tendency in the composite. In comparative relaxation tests up to 1000 h at approx. 50% short-term strength, carbon fiber reinforced plastics indicated virtually no creep, glass fiber reinforced plastics exhibited low creep (approximately twice as much as pre-tensioned steel, while aramid fiber reinforced plastics showed four to five times as much creep [1011]. 

P4 moderately reactive standard resin P7 highly reactive, heat-resistant resin 

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